Daniel Knowles writes for the Economist about politics and economics and is @dlknowles on Twitter.

Margaret Thatcher is the reason why people aren't interested in politics any more

The miners' strike - trade union strife gave people a political identity

Ever since George Galloway was elected to Bradford West two weeks ago, the Westminster classes have woken up to the fact that no one trusts them. I'm amazed it's taken so long. (I tend to read the comments underneath my blog posts, so I've known for some time that most people don't really like our current crop of politicians.)

But what's struck me recently is that it's not just these politicians that the public is disillusioned with – it's politics generally. Asking around in Birmingham last week, it was remarkable how many people said: "I don't care about politics". That's now not just acceptable, but common. According to the British Social Attitudes survey, only 56 per cent of people think that it's a duty to vote, while the number of people who think it's not worth voting has more than doubled since 1991, from 8 per cent to 18 per cent – reflecting the fact that turnout has collapsed since 1992. Meanwhile, those who do vote are also far more likely to vote for a third party – or now a fourth – simply to register a protest.

Yet if you ask people whether they think the country has problems, the response is a unanimous yes. We are worried about crime, about immigration, about stagnant salaries and the rising cost of living, about youth unemployment, about the NHS, about schools, about work conditions, about pensions. We just don't think that politicians can make any difference.

And I don't think that this a result of the particular uselessness of David Cameron or Ed Miliband, or their ilk. Rather, I reckon it's happening because our democratic institutions were built for a self-contained nation, which, day by day, is becoming more fragmented. That's not to say that we've been taken over by the EUSSR/the global plutocracy/third world Islamo-fascism (delete according to your preferred conspiracy theory). It's just that our national institutions – which politicians aspire to run – don't matter anywhere to people's everyday lives nearly as much.

As the historian Linda Colley points out, this is mostly Margaret Thatcher's fault. She opened up Britain's economy, and in the process, broke up many of the institutions by which we defined ourselves politically.

The National Union of Miners, and countless unions like it are all gone – wiped out in the battles of the 1980s. So too are British Gas, British Airways, British Telecom – they've all have been privatised, bought up by foreigners and made into multinational corporations. Simultaneously, the class system – which for most of a century had given people a distinctly British and political identity – has been thrown aside in favour of amorphous meritocracy. And then New Labour introduced devolution and loosened the immigration rules.

All of this has made us, in aggregate, better off, and Britain a more interesting, cosmopolitan place to live. But it has undermined our political identities. Until the 1990s, just going to work was a political act. Working-class miners, for example, had a strong political stake in the system – a reason to vote Labour and join the Labour Party. The middle-classes in the south, who didn't want to subsidise expensive coal, had a reason to vote Conservative to oppose them. Politics was a battle of interest groups, in a corporatist system. It may have made us poorer, but it gave people a strong incentive to be involved.

No longer. There is nothing political about being a call centre worker, or a hairdresser. Politics is now all about the swing voter – which means it's about being inoffensive, not interesting. Consequently, politicians are an increasingly professional, disconnected bunch. And that, I would say, is why our national politics has broken down. Actually, it's why the politics of nearly every modern, Western country, from France to the United States, has broken down. And honestly, I don't think there's much we can – or should – do about it.

Quick aside: Lots of readers have interpreted this as an attack on Thatcher. It's nothing of the sort. The point is that she won – she succeeded in rolling back the reach of the state, and breaking the political power of unions and state-corporations alike. The consequence of that is that people no longer have the direct interest in politics that they did. That's a good thing, no?